Air pack.

[kooldadd]

Real quick... does the air go through the j tube to the back of the pack when applying brakes and push diaphragm? I've searched for answers and diagrams. What I need is a flow diagram for air... I have air to the little boxy thing and no air out to j tube or trailer hookup.

 

[gimpyrobb]

Yes

It should anyway.

There is 2 versions, do you know which you have?

 

[kooldadd]

Old one. Plug in back of can. Long, I guess

 

[gimpyrobb]

http://www.steelsoldiers.com/showthread.php?40509-long-VS-short-airpack-pics&highlight=airpack

 

[gimpyrobb]

If theres a plug, its the old, long one.

 

[kooldadd]

Yeah. Put some oil back there to no avail... probably help to get air back there, huh?

 

[gimpyrobb]

Pull it apart before getting the rebuild kit, many are too rusted to fix.

If thats the case, I'd get the short style. Less parts to rebuild when the time comes.

 

[gimpyrobb]

Yeah. Put some oil back there to no avail... probably help to get air back there, huh?

yup

 

[kooldadd]

What makes the air flow through? I'm assuming it's a mechanical solenoid valve.

 

[gimpyrobb]

Its been too long since I've been into the old style.

Search for threads started by Rustystud, I'm pretty sure he has a step by step rebuild.

Edit, it was deuceswild:

http://www.steelsoldiers.com/showth...build-with-Photos!&highlight=air+pack+rebuild

 

[kooldadd]

10-4. Thanks

 

[rustystud]

What makes the air flow through? I'm assuming it's a mechanical solenoid valve.

When you push the master cylinder it applies pressure to a little valve that goes up and opens an air valve. The air valve then sends the air to the back of the air chamber (can) and applies the air piston which pushes the brake rod pressurizing the brakes fluid.

 

[rustystud]

The first picture shows the two styles of the hydraulic valve that pushes the air valve. The second picture shows the air valve and housing. The third picture shows the bore the hydraulic valve goes in. The main reason there is brake fluid in the air chamber is because of this valve. This valve is exposed to air on one side and brake fluid on the other. If the air side rusts the bore then when the valve is applied the rust tears the seal. Also this bore gets worn out and the seals don't work properly. When rebuilding the air-pak always make sure the seals are installed correctly on this valve. You will hear of guys who rebuilt their air-pak then have brake fluid in the air chamber immediately. In my opinion this is the weak link in the long style air-pak and the most over-looked item when rebuilding.

 

[kooldadd]

Fixed the air pack... removed it, took apart the cap where air hooks up, put a wrench on little nut (5/16"), and freed the plunger. Little wiggling and it moved freely. Reinstalled unit and it works. Need to bleed brake system and all should be good. Pump them a few times to get pedal and 1st gear / low range will stall out.

 

[kooldadd]

When you push the master cylinder it applies pressure to a little valve that goes up and opens an air valve. The air valve then sends the air to the back of the air chamber (can) and applies the air piston which pushes the brake rod pressurizing the brakes fluid.

If the brake lines have air, will that keep the air valve from opening? I have a really soft pedal that doesn't pump up hard. I know there's air in there, but I don't want to waste money on fluid if it's not going to do anything.

 

[porkysplace]

If the brake lines have air, will that keep the air valve from opening? I have a really soft pedal that doesn't pump up hard. I know there's air in there, but I don't want to waste money on fluid if it's not going to do anything.

If you have air anywhere in the hydraulic line portion of the brake system they will not work properly. This is a single circut brakes system which means any failure means complete loss of brakes and you want to cut corners on bleeding the brakes of a 14,000 pound truck to save a couple dollars ? If so you picked the wrong hobby. Since this was a non-runner truck when you got it and you have spongy brakes you need to do a full wheels and drums off brake inspection before putting it on the road.

Edit : When you opened the airpac you created a large air pocket in the system , the only way to remove the air is to bleed the entire system starting with the bleeder on the airpac then the farthest wheel from the M/C and work back to the M/C. This will take about a gallon of brake fluid . This is why you need to inspect the rest of the system or even rebuild the wheel cylinders (less than $10 per wheel) and know the condition of the brakes . You should also inspect the rubber lines.

 

[kooldadd]

If you have air anywhere in the hydraulic line portion of the brake system they will not work properly. This is a single circut brakes system which means any failure means complete loss of brakes and you want to cut corners on bleeding the brakes of a 14,000 pound truck to save a couple dollars ? If so you picked the wrong hobby. Since this was a non-runner truck when you got it and you have spongy brakes you need to do a full wheels and drums off brake inspection before putting it on the road.

Edit : When you opened the airpac you created a large air pocket in the system , the only way to remove the air is to bleed the entire system starting with the bleeder on the airpac then the farthest wheel from the M/C and work back to the M/C. This will take about a gallon of brake fluid . This is why you need to inspect the rest of the system or even rebuild the wheel cylinders (less than $10 per wheel) and know the condition of the brakes . You should also inspect the rubber lines.

I was only asking if air in the lines would keep the air pack from working so I could order one, if need be. The only thing I would be saving money on would be the fluid, because I would have to rebleed the system after replacement. I plan on in flushing the entire system when im sure its all working correctly. If i need to bleed it to check the air pack, then that's fine. Fluid isn't that expensive. Not really trying to cut corners on braking.

 

[kooldadd]

https://m.facebook.com/MidwestJeepWillys/ ordered air pack Monday. 459.95 SHIPPED! Should have it Friday. Cheapest I found.

 

[Jeepsinker]

Porky, I agree that the truck needs all the drums to be gone through, and a flush is in order as well, that being said....
There is no reason to use a gallon of fluid to bleed the brakes on any of these trucks. Not unless the system is dry.
I have replaced master cylinder, all 6 wheel cylinders, and air pack on multiple trucks and never used more than two quarts of fluid.
Beyond that, I've also never needed to bleed at the air pack.

 

[kooldadd]

Everything gone through... good to go. I did use just under a gallon on mine just to make sure everything was flushed out good. Shouldn't need that much to rebleed after air pack install